| 1 | /* xalloc-oversized.h -- memory allocation size checking |
| 2 | |
| 3 | Copyright (C) 1990-2000, 2003-2004, 2006-2014 Free Software Foundation, Inc. |
| 4 | |
| 5 | This program is free software: you can redistribute it and/or modify |
| 6 | it under the terms of the GNU General Public License as published by |
| 7 | the Free Software Foundation; either version 3 of the License, or |
| 8 | (at your option) any later version. |
| 9 | |
| 10 | This program is distributed in the hope that it will be useful, |
| 11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 13 | GNU General Public License for more details. |
| 14 | |
| 15 | You should have received a copy of the GNU General Public License |
| 16 | along with this program. If not, see <http://www.gnu.org/licenses/>. */ |
| 17 | |
| 18 | #ifndef XALLOC_OVERSIZED_H_ |
| 19 | # define XALLOC_OVERSIZED_H_ |
| 20 | |
| 21 | # include <stddef.h> |
| 22 | |
| 23 | /* Return 1 if an array of N objects, each of size S, cannot exist due |
| 24 | to size arithmetic overflow. S must be positive and N must be |
| 25 | nonnegative. This is a macro, not a function, so that it |
| 26 | works correctly even when SIZE_MAX < N. |
| 27 | |
| 28 | By gnulib convention, SIZE_MAX represents overflow in size |
| 29 | calculations, so the conservative dividend to use here is |
| 30 | SIZE_MAX - 1, since SIZE_MAX might represent an overflowed value. |
| 31 | However, malloc (SIZE_MAX) fails on all known hosts where |
| 32 | sizeof (ptrdiff_t) <= sizeof (size_t), so do not bother to test for |
| 33 | exactly-SIZE_MAX allocations on such hosts; this avoids a test and |
| 34 | branch when S is known to be 1. */ |
| 35 | # define xalloc_oversized(n, s) \ |
| 36 | ((size_t) (sizeof (ptrdiff_t) <= sizeof (size_t) ? -1 : -2) / (s) < (n)) |
| 37 | |
| 38 | #endif /* !XALLOC_OVERSIZED_H_ */ |